Pip-OS/docs/HARDWARE.md

PIP-OS Hardware Guide

Supported Configurations and Pin Assignments

Overview

PIP-OS supports three tiers of Pip-Boy hardware configurations, each targeting different Raspberry Pi models and feature sets.

Tier 1: Basic Pip-Boy (Raspberry Pi Zero/1)

Specifications

• SoC: BCM2835 (ARMv6)
• CPU: Single-core ARM1176JZF-S @ 700MHz
• RAM: 512MB
• Display: 320x240 SPI TFT (ILI9341 or ST7789)
• Input: 5 buttons + rotary encoder
• Audio: PWM through GPIO
• Sensors: RTC module (DS3231 via I2C)
• Power: 2x AA batteries or single 18650

GPIO Pin Assignment

Display (SPI0):
  MOSI  - GPIO 10
  MISO  - GPIO 9
  SCLK  - GPIO 11
  CS    - GPIO 8
  DC    - GPIO 24
  RST   - GPIO 25

Buttons:
  UP    - GPIO 17
  DOWN  - GPIO 27
  LEFT  - GPIO 22
  RIGHT - GPIO 23
  SELECT- GPIO 4

Rotary Encoder:
  A     - GPIO 5
  B     - GPIO 6
  PRESS - GPIO 13

Audio (PWM):
  OUT   - GPIO 18 (PWM0)

I2C (RTC):
  SDA   - GPIO 2
  SCL   - GPIO 3

Power:
  BATTERY_SENSE - GPIO 26 (ADC via voltage divider)

Display Connection

For ILI9341 320x240 TFT:

TFT Pin → Pi Pin
VCC     → 3.3V
GND     → GND
CS      → GPIO 8
RESET   → GPIO 25
DC/RS   → GPIO 24
MOSI    → GPIO 10
SCK     → GPIO 11
LED     → 3.3V (with 100Ω resistor)
MISO    → GPIO 9 (optional)

Power Circuit

Battery (3-4.2V) → LDO 5V → Pi
                         ↓
                  Voltage Divider → GPIO 26
                  (R1: 2kΩ, R2: 1kΩ)

Tier 2: Standard Pip-Boy (Raspberry Pi 2/3)

Specifications

• SoC: BCM2836 (Pi 2) or BCM2837 (Pi 3)
• CPU: Quad-core Cortex-A7 @ 900MHz (Pi 2) or Cortex-A53 @ 1.2GHz (Pi 3)
• RAM: 1GB
• Display: 480x320 SPI TFT or 640x480 HDMI
• Input: Full button set (10 buttons) + rotary encoder + optional touch
• Audio: I2S DAC (PCM5102A or similar)
• Sensors: RTC, GPS (UART), Accelerometer (I2C), Geiger counter
• Power: 18650 Li-Ion with charging circuit

GPIO Pin Assignment

Display (SPI0):
  (Same as Tier 1)

Buttons:
  UP     - GPIO 17
  DOWN   - GPIO 27
  LEFT   - GPIO 22
  RIGHT  - GPIO 23
  SELECT - GPIO 4
  A      - GPIO 16
  B      - GPIO 20
  X      - GPIO 21
  Y      - GPIO 12
  START  - GPIO 19

Rotary Encoder:
  (Same as Tier 1)

Audio (I2S):
  LRCLK - GPIO 19 (conflicts with START, use separate IC)
  DIN   - GPIO 21
  BCK   - GPIO 18

I2C (Sensors):
  SDA   - GPIO 2
  SCL   - GPIO 3

GPS (UART):
  TX    - GPIO 14
  RX    - GPIO 15

Geiger Counter:
  PULSE - GPIO 7 (interrupt input)

Power Management:
  BATTERY_SENSE - GPIO 26
  CHARGE_STATUS - GPIO 24
  POWER_GOOD    - GPIO 25

I2S Audio Connection

For PCM5102A DAC:

DAC Pin → Pi Pin
VCC     → 3.3V
GND     → GND
BCK     → GPIO 18
DIN     → GPIO 21
LRCK    → GPIO 19
SCK     → Not connected
FLT     → GND
DEMP    → GND
XSMT    → 3.3V

GPS Module Connection

For NEO-6M or similar:

GPS Pin → Pi Pin
VCC     → 3.3V
GND     → GND
TX      → GPIO 15 (Pi RX)
RX      → GPIO 14 (Pi TX)

Tier 3: Deluxe Pip-Boy (Raspberry Pi 4)

Specifications

• SoC: BCM2711
• CPU: Quad-core Cortex-A72 @ 1.5GHz
• RAM: 2-8GB
• Display: 800x480 HDMI touchscreen or large TFT
• Input: Capacitive touch + full button set + encoder
• Audio: High-quality I2S DAC + Bluetooth
• Sensors: Full sensor suite (RTC, GPS, IMU, Geiger, temp, heart rate)
• Power: Dual 18650 with advanced power management

Additional Features

• Bluetooth for wireless holotape sync
• Wi-Fi for online features (when available)
• USB-C charging with fast charge support
• RGB LED indicators
• Haptic feedback motor

Extended GPIO Assignment

Touch Controller (I2C):
  SDA   - GPIO 2
  SCL   - GPIO 3
  INT   - GPIO 27

IMU (I2C):
  (Shared with touch)
  
Heart Rate Sensor (I2C):
  (Shared with touch)

Haptic Motor (PWM):
  CTRL  - GPIO 13 (PWM1)

RGB LEDs (WS2812B):
  DATA  - GPIO 10

USB-C Power:
  PD_INT - GPIO 26

Display Options

SPI TFT Displays

ILI9341 (320x240)

• Speed: Up to 40 MHz SPI
• Colors: 262K (18-bit)
• Touch: Optional resistive overlay
• Power: ~100mA @ 3.3V

ST7789 (240x240 / 320x240)

• Speed: Up to 62.5 MHz SPI
• Colors: 262K (18-bit)
• Touch: Optional capacitive
• Power: ~80mA @ 3.3V

HDMI Displays

480x320 DSI/HDMI

• Official 3.5" touchscreen
• Capacitive touch (10-point)
• Power via Pi

800x480 HDMI

• 7" HDMI display
• Capacitive or resistive touch
• External power recommended

Sensor Modules

RTC Module (DS3231)

Module  → Pi
VCC     → 3.3V
GND     → GND
SDA     → GPIO 2
SCL     → GPIO 3
32K     → Not connected
SQW     → GPIO 4 (optional alarm)

• I2C Address: 0x68
• Battery backup: CR2032
• Accuracy: ±2ppm

GPS Module (NEO-6M)

• Update rate: 1-10 Hz
• Accuracy: 2.5m CEP
• Cold start: ~30s
• Warm start: ~1s
• UART: 9600 baud (default)

Accelerometer (MPU6050/LSM303)

• I2C Address: 0x68 or 0x19
• Range: ±2g to ±16g
• Update rate: Up to 1kHz
• Features: 3-axis accel + gyro

Geiger Counter Interface

Counter Pin → Pi Pin
VCC         → 5V
GND         → GND
PULSE       → GPIO 7

• Pulse: Active high, ~100μs width
• Count pulses to calculate CPM
• Use interrupt for accurate counting

Power Management

Battery Configuration

Single 18650 (Tier 1/2)

18650 → Protection Board → Boost Converter (5V) → Pi
  ↓
Voltage Divider → GPIO 26 (monitor)

Dual 18650 (Tier 3)

2x 18650 (Series) → BMS → Buck Converter (5V) → Pi
  ↓
Fuel Gauge (I2C) → Monitor

Charging

For single-cell LiPo/18650:

USB-C → TP4056 Charge Controller → Battery
          ↓
     CHRG/DONE → GPIO (status LEDs)

For dual-cell:

USB-C → BMS with charging → Batteries
          ↓
     Status signals → I2C/GPIO

Power Consumption

Mode	Tier 1	Tier 2	Tier 3
Active	400mA	800mA	1.2A
Idle	250mA	500mA	800mA
Sleep	100mA	150mA	200mA
Deep Sleep	50mA	50mA	50mA

Battery Life Estimates

With 3000mAh 18650:

• Tier 1 Active: ~7 hours
• Tier 2 Active: ~3.5 hours
• Tier 3 Active (dual): ~5 hours

Assembly Notes

Enclosure Considerations

• Waterproofing: IP54 recommended
• Button placement: Ergonomic for wrist mount
• Display viewing angle: 45° optimal
• Weight: <300g for wearability

Thermal Management

• Pi 3/4 may need heatsink
• Passive cooling preferred
• Vents for air circulation
• Keep away from battery

Mechanical

• Shock absorption for display
• Strain relief for wiring
• Mounting holes for PCB
• Easy access to SD card

Testing and Calibration

Display Calibration

1. Check SPI clock speed
2. Verify orientation
3. Test touch accuracy (if applicable)
4. Adjust brightness

Input Testing

# Test buttons
evtest /dev/input/event0

# Test rotary encoder
evtest /dev/input/event1

Sensor Calibration

1. RTC: Set time, verify drift over 24h
2. Accelerometer: Six-position calibration
3. GPS: Wait for fix, check accuracy
4. Battery: Calibrate voltage divider

Troubleshooting

Display Issues

• Black screen: Check power, SPI connections
• Scrambled display: Verify SPI speed, check wiring
• Touch not working: Test I2C, check driver

Input Issues

• Buttons not responding: Test with multimeter, check pull-ups
• Encoder not working: Verify both channels, check debouncing
• Ghost inputs: Add debouncing capacitors

Power Issues

• Won't boot: Check 5V rail, verify current capacity
• Random resets: Add decoupling capacitors
• Low battery voltage: Check voltage divider, calibrate ADC

Audio Issues

• No sound: Verify I2S/PWM config, check amplifier
• Distorted audio: Check sample rate, reduce volume
• Noise: Add filtering, improve power supply

Parts List

Tier 1 Basic Kit

• Raspberry Pi Zero W
• 320x240 SPI TFT
• 5x tactile buttons
• Rotary encoder with button
• DS3231 RTC module
• Passive buzzer
• 18650 battery holder
• TP4056 charger module
• 5V boost converter
• Resistors, capacitors, wire

Estimated cost: $60-80

Tier 2 Standard Kit

• Raspberry Pi 2 or 3
• 480x320 SPI TFT
• 10x tactile buttons
• Rotary encoder
• DS3231 RTC
• PCM5102A I2S DAC
• NEO-6M GPS
• MPU6050 IMU
• Geiger counter module (optional)
• 18650 battery + BMS
• Buck converter
• Enclosure

Estimated cost: $120-180

Tier 3 Deluxe Kit

• Raspberry Pi 4 (4GB)
• 800x480 HDMI touchscreen
• Touch controller
• 10x buttons + encoder
• Full sensor suite
• High-quality DAC
• 2x 18650 + BMS
• USB-C PD
• RGB LEDs
• Haptic motor
• Premium enclosure

Estimated cost: $250-350

Resources

• Raspberry Pi Pinout
• BCM2835 Datasheet
• ILI9341 Driver
• PCM5102A Datasheet

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